Electromagnetic device



April 26, 1932.

N. C. SHAW ELECTROMAGNETIC DEVICE FilGd Sept. 23, 1951 INVENTOR.

M C. S '7 a W By 611W Ma ATTORNEY.

Patented Apr. 26, 1932 UNITED STATES PATENT OFFICE NOBLE C. SHAW, OF EDGEWOOD, PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH 8c SIGNAL COMPANY, OF SVTISSVALE, PENNSYLVANIA, A CORPORATION OF PENNSYL- VANIA ELECTROMAGNETIC DEVICE Application filed September 23, 1931.

3 United States N 0. 17,252, granted to Snavely & Wells on April 2, 1929, for electrical relays.

I will describe two forms of electromagnetic devices embodying my invention, and Will then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a view showing in front elevation one form of device embodying my invention. Fig. 2 is a top plan view of the magnets A and B of the device illustrated in Fig. 1. Fig. 3 is a diagrammatic view showing one circuit arrangement which may be used with the de-' vice shown in Figs. 1 and 2. Fig. 4 is a view showing a modification of the device shown in Fig. 1 and also embodying my invention. Similar reference characters refer to similar parts in each of the views.

Referring first to Figs. 1 and 2, the device in the form here shown comprises an armature C pivotally mounted on fillLXlS 7 and operated by two electromagnets A and B. Each" of the magnets A and B comprises the usual cores provided with windings 1 and 2, which cores are connected by a backstrap 3 and terminate in pole pieces 4 and 5. The partsiare so proportioned and disposed that the-pivotal axis of the armature C is between and above the magnets A and B. It will, therefore, be clear that when magnet A is energized armature C is swung to the right or in clockwise direction as viewed in 1, and when magnet B is energized the armature is: swung to the left or in counter-clockwise direction.

Attached to the upper side of armature C is a supporting member G of insulating material carrying a contact arm 12, which coacts with two fixed contact fingers 13 and 14. When the armature is swung to the right, contact 12-13 is closed; when the armature is swung to the left, contact 12-14 is closed; and when the armature is in an intermediate position, contacts 12-13 and 12-14 are both 0 open.

Serial No. 564,599.

A small weight 20, of non-magnetizable material, is attached to the right-hand side of armature O to bias the armature to a position in which contact 12-13 is closed when the device is deenergized.

Referring to Fig. 3 of the drawings, the windings 1 and 2 of both magnets A and B are connected in series and are supplied with current from terminals D and E of a source of current which is not shown in the drawings. It will be seen from the wiring dia gram, however, that when contact 12-14 is closed, windings 1 and 2 of magnet B are placed on short circuit; and that when contact 12-13 is closed, windings 1 and 2 of magnet A are placed on short circuit. The supply of current to the device may be controlled in any suitable manner, such as by a switch Q.

lVhen switch Q is open, the parts occupy the positions in which they are shown in the drawings, that is to say, armature G is swung to the right to close contact 12-13. If now switch Q, is closed, current will flow through the windings of magnet B, but contact 12-13 being closed, the windings of magnet A are placed on short circuit, and so this magnet does not become energized. The energization of magnet B will cause armature C to swing about its axis 7 until its left-hand leaf engages the core pins 19 of magnet B. During this movement, however, contact 12-13 will open and contact 12-14 will close. The closing of contact 12-14 will place the windings of magnet B on short circuit, and the field of this magnet will commence to decay. Due, however, to the short-circuited condition of the windings of magnet B, this decay will be comparatively slow. The decay of the field will be further retarded by the low reluctance of the magnetic circuit, armature C now being adjacent the pole pieces 4 and 5 of the magnet B and thus decreasing the air gaps between these poles and the armature. The opening of contact 12-13 has in the meantime allowed magnet A to become energized, and after an interval of time the torque exerted by the decreasing flux of magnet B will be overbalanced by the torque exerted by the flux in magnet A, and the armature will then. swing in. clockwise direction until its right-hand leaf engages the core pins 19 of magnet A. This oscillatory motion of armature C will continue as long as switch Q is closed.

Attached to the armature C is a magnetizable shunting bar 6, which bar is located in such position as to be moved toward and away from the poles of each magnet according as the armature is swung toward and away from the poles of the other magnet. That is to say, when armature C is in the position shown in Fig. 1, bar 6 bridges the poles at and 5 of magnet B and is spaced from these poles by only a small air gap; whereas, when armature C is swung to its other extreme position, the bar 6 will bridge the poles of magnet A, being spaced from these poles by only a small air gap. When the air gap between bar 6 and the poles of either magnet is minimum, the air gap between this bar and the poles of the other magnet is maximum. As here shown, the bar 6 is supported on the underside of armature '0 directly beneath the pivotal axis 7 and is spaced from the armature by a block 22 of non-magnetizable material. This specific structure is not essential, however, and the bar 6 may, if desired, be attached directly to the armature C, without the provision of the intermediate block 22.

Assuming again that the parts of the device are in the positions in which they are shown in Fig. 1, and that switch Q, becomes closed, it will be observed that the reluctance of the magnetic circuit of magnet B is relatively low, because of the small air gap between the poles of this magnet and the bar 6. It follows that the reactance of windings 1 and 2 of magnet B is high, and that, con sequently, the building up of the current through these windings will be relatively slow. Due to this fact, reversal of armature C will require a greater interval of time than if the shunting bar 6 were not provided. Furthermore, it will be observed that this shunting bar is attracted by the poles of magnet B, thereby still further increasing the length of time required to reverse armature C. The parts are so proportioned, that eventually the pull exerted by magnet B on arm ature C will overbalance the pull on bar 6, and the armature will then reverse. When armature C does reverse, the bar 6 will be shifted into close relationship with the poles of magnet A, so that the building up of current in the windings of magnet A will be delayed due to the low reluctance of the magnetic circuit for this magnet, and the operation of armature C will be still further delayed due to the magnetic attraction of the bar 6 by the magnet A.

It may sometimes be desirable to reduce, or even substantially eliminate, the torque exerted on the armature by the magnetic attraction of each magnet for the shunting bar 6, and when this is so a modified structure such as that shown in Fig. 4 may be used. Referring to this view, the parts are the same as in Fig. 1, except for the cooperating faces of the pole pieces and the shunting bar. Each pole piece at has a face 25 which is substantially perpendicular to a line 27 passing through the pivotal point 7 of the armature,

and the shunting bar 6 has two faces 26 which register with, and are parallel to, the face 25 of one pole piece or the other according as the armature is in one position or the other. By means of this construction, it will be seen that little or no torque is applied to the armature due to magnetic attraction between the pole pieces and the shunting bar, and yet the shunting bar accomplishes its purpose in so far as affecting the reluctance of each magnet is concerned. It will be obvious that any desired amount of magnetic torque on the shunting bar between maximum and zero values may be provided for by choosing a suitable design lying between the two extremes shown in Figs. 1 and 4.

One advantage of devices embodying my invention, is the fact that the magnetic shunting bar is effective only during the time that it is desired to retard the reversal of the armature C, this bar being moved with the armature so that it does not divert any appreciable amount of the flux which is" serving to hold the armature in either of its extreme positions. Due to the fact that the bar is carried by the armature, a device of a given size may be made slower in operation than when the poles of each magnet are shunted by fixed members.

Although I have herein shown and described only one form of device embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. An electromagnetic device comprising a pivoted armature, two electromagnets one on each side of the pivotal axis of said armature whereby the armature is swung in one direction or the other according as one magnet or the other is energized, means effective when the armature is swung toward either magnet for placing the Winding of the other magnet on short circuit, and a magnetizable shunting bar carried by said armature in such position as to be moved toward and away from the poles of each magnet according as the armature is swung toward and away from the poles of the other magnet.

2. An electromagnetic device comprising a pivoted armature, two electromagnets one on each side of the pivotal axis of said armature whereby the armature is swung in one direction or the other according as one magnet or the other is energized, a circuit including a source of current and the windings of said two magnets connected in series, means efiective when the armature is swung toward either magnet for placing the winding of the other magnet on short circuit, and a magnetizable shunting bar carried by said armature in such position as to be moved toward and away from the poles of each magnet according as the armature is swung toward and away from the poles of the other magnet.

3. An electromagnetic device comprising a pivoted armature, two electromagnets one on each side of the pivotal aXis of said armature whereby the armature is swung in one direction or the other according as one magnet or the other is energized, and a magnetizable shunting bar carried by said armature in such position as to be moved toward and away from the poles of each magnet according as the armature is swung toward and away from the poles of the other magnet.

4:- An electromagnetic device comprising a pivoted armature, two electromagnets one on each side of the pivotal axis of said armature whereby the armature is swung in one direction or the other according as one magnet or the other is energized, and a magnetizable shunting bar carried by said armature in such position as to be moved toward and away from the poles of each magnet according as the armature is swung toward and away from the poles of the other magnet, the cooperating faces on each pole and the shunting bar being substantially perpendicular to a line passing therethrough and through the pivotal point of the armature, whereby minimum torque is exerted on the armature due to the shunting bar.

In testimony whereof I aflix my signature.

NOBLE C. SHAW. 

